Telephone-receiver



(No Model.)

0. SELDEN.'

TELEPHONE EEGE IVEE. I No. 515,797. Patented Mar. 6, 1894.

ATTEST: INVENTUE;

Charles Sudan,

UNITED STATES PATENT OFFICE,

CHARLES SELDEN, or BALTIMORE, MARYLAND.

TELEPHONE-RECEIVER.

SPECIFICATION forming part Of Letters Patent N0. 515,797, dated March 6,1894.

Application filed December 10, 1889. Serial No. 388i 9- (H -l v To allwhom it may concern.-

Be it known that 1, CHARLES SELDEN, a citizen of the United States, anda resident of Baltimore, in theState of Maryland,have invented a certainnew and useful Telephone-Receiver,of which thefollowing isaspecification.

My invention relates to telephone receiving apparatus designed for useon telephone hnes in connection with a telephone transmitter of anydesired construction but more especially adapted for use with atelephone transmitter in which the transmitting contacts are of metal asin the form of transmitter hereinafter referred to.

My invention consistsin a novel compound telephone receiving apparatusin which two or more electro magnets are properly cornbincd or connectedto act in conjunction for producing the sound impulses, the'magneticpulses of the several magnets being however made to follow or be delayedone beyond the other slightly instead of being substantially coincidentor simultaneous in all the magnets. This dissimultaneous or successiveaction I bringaboutthrough electricinduction. Thus, for instance, in thecase of a compound telephone receiver having two magnets, one of suchmagnets would be energized by electric impulses following orcorresponding to the electrical changes produced by the transmitter,while the second magnet would be energized by impulses inductivelyproduced by the currents which flow in the coils of the first magnet orby currents exactly following or coincident with the same. In case theinvention be extended to include a series of three or more magnets, eachmagnet of the series would receive its energizing electric impulse byinduction from the circuit including the coil of the preceding magnet ofthe series or by induction from a circuit where the electric impulsesexactly follow or coincide with those which energize suchpreceding'magnet.

My invention is applicable to any form of telephone receiver, though forthe sake of illustration I have herein illustrated it as carried out inconnection with a receiver wherein a diaphragm is employed.

I prefer, in carrying out the invention, to generate the series ofinduced impulses for the successive magnets of the receiver by means ofcoils each placed on the magnet core of a preceding magnet in the seriesand connected to the energizing coil of the succeeding magnet. Theeffect of energizing the magnets in rotation by inductive actionstransmitted from one to the other of the series of circuits is in effectto slightly prolong the action of any received electric impulsegenerated ortransmitted over the line.

or bridge over the efiects produced by sharp termittent currents orelectrical pulsations maybe severe or sudden enough to produce in anordinary receivera confused orinarticulate sound, they will each, in myform of receiving apparatus, produce magnetic effects for eachelectrical impulse which will exist in the receiver as pulsationsfollowing or succeeding each other so as to be blended into a singleimpulse, and the practical use of a telephone apparatus will becomefeasible although its transmitter may be so delicately adjusted as toproduce frequent makes and breaks of the circuit when spoken intoforcibly.

In the accompanying drawingsz-Figure 1, is a diagrammatic viewillustrating my invention. Fig. 2, is a plan of a series of magnets in areceiver embodying myinvention. Fig. 3, illustrates in side elevation amodification in the manner of arranging the several magnets. Fig. 4:,illustrates a modification in the manner of producing the successiveelectric inductions from one to the other of the magnets'or magnetcircuits.

Referring to Fig. l, L, indicates an electric line of any desiredconstruction connecting a telephone transmitter A, and the receivinginstrument B, of my invention. C,indicates the diaphragm of atelephoneupon which act the several magnets D, D, D &c. These magnetsare properly mounted in any support or casing as well understood in theart with their poles presented to the diaphragm or armature. Thissupport or casing is of nonmagnetic material so that the cores of 'themagnets are practically independent of one another or are free from amagnetic induction from one to the other which would cause them tooperate practically as one magnet through the action of any currentcirculating in the coil of either.

By my invention there is a tendency to tide or sudden pulsations so thatalthough the in- In the form of my invention shown in Fig. 1, theelectrical induction from the circuit of the coil of one electro magnetto the circuit of the next is produced by the agency of coils on thecores of said magnets. The main line coil of magnet D, is included inthe line circuit to earth as shown, but upon the core of said magnet isplaced an additional coil subject to the electric induction of the firstand connected in turn with a coil for energizing magnet D. Theenergizing coil of magnet D is connected to a coil on the core of D,which latter coil acts as the secondary to the energizing coil of saidmagnet. of magnets may be joined in series and inductively related asdescribed, and may be disposed in any desired manner with relation tothe diaphragm or in a suitable sound case or resonator. I

As shown in Fig. 2, the magnets are arranged concentrically around acentral magnet which may be the line magnet or one which receives theprimary inducing impulse flowing over the line circuit. If it is desiredto concentrate the magnetic actions upon the center of the diaphragm thecores of the outside magnets may have their poles prolonged so as tosurround the pole of the central magnet as illustrated in Fig. 3.

The telephone transmitter which I prefer to employ is provided with twocontacts or electrodes E, F, of metal such for instance as platinum,though other materials may be employed. One of the electrodes, as F,consists of a wire brush which has a bias toward the opposite electrodeE, through any suitable influence as a spring or gravity. The electrodeE, may have a plain or roughened surface upon which F, bears. Thecircuit from the batteryor generator M, B, is through said electrodes asindicated to line and through the coils of magnet D, to the earth orreturn circuit. The form and manner of mounting the electrodes areimmaterial and maybe va ried indefinitely. On the production of anyelectric pulse or change of electrical condition on the line L, themagnet D, will be energized. Attendant upon such action is thedevelopment of an electric impulse in the coils connected with theenergizing coil of magnet D, which impulse in turn results in theproduction of an energizing impulse for magnet D and so on through theseries of magnets in such way as to slightly'prolong the primaryenergizing effect which would be produced alone if magnet D, were alonedepended upon to set up, an audible impulse.

If but one. magnet were employed or a seriesof magnets whose cores arein sufficiently close inductive proximity to make them opcrate assubstantially one magnet, then any single electrical pulse or vibrationin the coils of the magnet would cause the diaphragm to move from itsnormal position and allow it to return to normal position instantly, theperiod of its to and fro movement coinciding substantially with theperiod of the pulse or Any numbervibration. In my invention, however,such an electric pulsation would have the same effect upon the diaphragmand the diaphragm would at once return to its normal position were itnot for the fact that immediately following and in succession, othermagnets are energized having an elfect upon the diaphragm and allowingit to return to its normal position gradually and by degrees rather thaninstantly and violently as in other systems. The effect is, therefore, apractical retention of control over the diaphragm for a greater periodof time for the same initial pulsation, and this prolongation is suchthat a cessation of pulsation on the main line would be permitted andyet the diaphragm would be controlled or held up to a certain extent bythe additional magnets, and tone and speech, which would be otherwiselost become intelligible owing to the diaphragm returning to its normalposition, are, reproduced.

I find in practice that exceedingly beneficial effects are produced bythe employment of a compound receiver such as hereinbefore described inthose cases where with ordinary forms of receiver the action of thetransmitter is such as to produce sounds which are so confused as tomake the apparatus. practically useless. This beneficial efiect Iattribute to the prolongation of each pulse through the succession ofinductive actions before, described, but it is to be understood that Ido not bind myself to such theory of action since it is possible thatthe edectis noted by me may be due to other interactions or combinedeffects of the magnets energized at different points in a train ofinductive operations.

The form of receiver shown works well with the form of transmitterdescribed.

In the form of receiver shown in Fig. 3, the several magnets areconnected at their rear by a non-magnetic yoke N, in which the cores aresecured. The same. non-magnetic yoke practically exists in the form ofreceiver shown in Figs. 1, and 2, where the magnet cores are supposed torestin a wooden case.

In Fig. 4, I have illustrated a way in which the same electrical andmagnetic effects may be produced by the employment of a separateinduction coil I, which contains, as aprimary, a. coil in the circuitwith the energizing coil of magnet D,v and has as a secondary the coilwhich is connected to the energizing circuit of the magnet D In caseother magnets were employed it would be. necessary, according to theplan shown in Fig.4, to use another induction coil as I, shown in dottedlines the primary of which would be connected into the circuit with theenergizing coil of D. By this means the before described succession ofinductive actions could be produced obviously with the same practicaleffect as in the case of Fig. 1. It will be seen that in the case ofFig. 1, the coils and cores connected as described are practicallyinduction coils, each energizing coil for the magnet being likewise aprimary while the coil on the same core connected to the next energizingcoil is the secondary therefor.

What I claim as my invention is- 1. In a telephone receiver'two or moremagnets having magnetically independent cores and operating inconjunctionbut in immediate succession to produce sound impulses, one

of said magnets having a coil which carries currents received from theline while the othare are excited in succession by inductive currents ofthe first, second, third, &c., order primarily induced from the linecurrent.

proximity to the centerof the diaphragm constituting the'armature of themagnet.

4. The combination inatelephone receiver,

of a diaphragm and two or more magnets the pole ends of which aredisposed near the diaphragm, said magnets being connected and placed incircuits forming links in a chain of induction, as and for the purposedescribed.

5. The herein described improvement in reproducing vocal soundscorresponding to electric pulsations sent from a transmitter, consistingin setting up by said pulsations atrain of consecutive electricinductions and producing the mechanical sound effects by the compoundaction of consecutive magnetic pulsations developed individually byelectric pulsations which being at diiferent parts of the train ofelectric inductions are definitely displaced or delayed behind oneanother.

, Signed at Baltimore city and State of Mary- 45 land, this 9th day ofDecember, A. D. 1889.

CHARLES SELDEN. Witnesses:

MURRAY HANSON, WILLIAM H. BERRY.

